We report on the fabrication and characterisation of the very first direct electron transfer-based glucose/oxygen biofuel cell (BFC) operating in neutral glucose-containing buffer and human serum. Corynascus thermophilus cellobiose ehydrogenase and Myrothecium verrucaria bilirubin oxidase were used as anodic and cathodic bioelements, respectively. The
following characteristics of the mediator-, separator- and membrane-less, a priori, non-toxic and simple miniature BFC, was obtained: an open-circuit voltage of 0.62 and
0.58 V, a maximum power density of ca. 3 and 4 lW cm–2 at 0.37 and 0.19 V of cell voltage, in phosphate buffer and human serum, respectively.